OXNARD, Calif. -- Football coaches like to say that injuries present opportunities for other players. While that is true for the Dallas Cowboys, suspensions also present opportunities.

Randy Gregory is out for the season because of multiple violations of the NFL’s substance-abuse policy. David Irving will miss the first four games of the season after violating the league’s policy on performance-enhancing drugs. Damontre Moore will miss the first two games because of a substance-abuse policy investigation.

Gregory’s suspension might have led to the Cowboys adding Moore in the offseason as a free agent, but all three would have been valuable parts to a defensive line rotation in 2017.

Gregory played in just 13 games in his first two seasons, mostly because of suspensions. He has recorded just one sack, but the Cowboys had hoped things would eventually work out to where the former second-round pick would get a chance to play again. Nobody knows for sure if that will happen. The team can have only minimal contact with him during the suspension. (He is eligible to return after the season.)

The Cowboys knew Moore’s suspension was a possibility because of an arrest last December when he played for the Seattle Seahawks, but Irving’s suspension was a surprise.

“I winded up taking some products that had a banned substance,” Irving said. “The substance wasn’t listed on the bottle. It happens, and it happened to me. You live, learn and move on.”

Moore apologized for his mistake

"I made my bed, and I've got to lie it in," he said. "I just wanted to apologize to the Cowboys organization and the fans for my past even following me. I also want to show them by coming here and working hard each and every day that I'm here to make the best of this opportunity."

Gregory is not allowed at training camp, but Irving and Moore can practice and play in preseason games. Starting the first week of the season they will be banished. And that has created opportunity.

So far in camp, Tyrone Crawford and DeMarcus Lawrence have lined up as the starting left and right defensive ends. Benson Mayowa, who led the Cowboys in sacks last year with six, has been working at right defensive end in the nickel defense. The Cowboys drafted Taco Charlton in the first round to help the pass rush immediately. With the suspensions, they will count on him even more.

Charles Tapper did not play as a rookie in 2016 because of a back injury. The Cowboys hope his speed can help them get to the quarterback. Lenny Jones, Lewis Neal and Richard Ash may not have had the cleanest routes to making it at the start of camp, but the losses of Moore and Irving open a spot on the roster, if not two.

“I like our depth that we’ve got in the defensive front as far as some of the guys that won’t be with us early there,” team owner and general manager Jerry Jones said. “That’s promising.”

But the Cowboys don’t have that “war daddy” he craves so badly.

“Let me say this, there’s parts of one out there, I know that,” Jones said. “Now it may take three of them to get him, but he’s out there. I’m talking about the rotation of the numbers. I like our numbers. I see how we can play. Some of the greatest successes that I’ve had with the Cowboys was when we’ve had a defensive line rotation. I’ve always looked for the promise of that.”